The snorkel is preferable to the reg on some shore dives involving a surface swim because it allows one to look straight ahead, and negotiate obstacles and not use tank air.
Those reasons are good enough for me to justify recommending snorkel use for shore dives. I also recommend that snorkels are carried on ocean dives. I don't have one attached to the mask in the ocean, but I carry one in case I am forced to ditch equipment and swim. Shikata-ga nai is not an option in the open sea when/if things go wrong.
Being realistic means showing awareness. I would argue that you are not in that you are arguing through your own confined situation of being an instructor teaching Japanese tourists, which is not indicative of the diving world as a whole. That, is being obtuse. I'm yet to hear the statistics in snorkel use leading to diver accidents, which one would assume would be rampant seeing as many divers continue to use them even though they are "stupidly dangerous".
When the situation means using a snorkel to benefit the user, then by all means use the snorkel. If as a diver, you can not use a snorkel, then don't. The snorkel is a tool, nothing more, nothing less.
しょうがないって.誰も分からへんよ．
This is continuing to make the assumption that snorkels are 'safety equipment' for regular divers, even when presented with reasons to think otherwise.
First let's analyze the shore dive:
Am I picturing the dive correctly? I am assuming I am.
I am picturing it as the fringing reef with cuts where an outgoing tide, and the return water from the waves, creates, at times, the conditions you mentioned earlier where turning the head sideways can pull the mask off or at least away from the face, and having a snorkel makes that more likely.
Fair enough, then, to also say that the only reason to use the snorkel on those shore dives (rather than a reg) is (only) to save air. My argument there is that the amount of air you are saving is so minimal as to be unimportant, since the return has to be planned with the assumption that you might have to come back on scuba. And given the fact that on the return, a snorkel makes mask leakage a real problem at a time when the divers have both hands are busy makes me take the snorkels off of divers before that dive to prevent problems.The places I have dove like that, both hand are often busy with the rope placed to get divers back, or some bottom feature to make return even possible.
Assuming we are doing the same type of dive, you choose saving a small amount of air, and I choose mask security. In other words safety is against the snorkel.
With regards to Japanese, almost all my students are Japanese, but the fun divers are from
everywhere. The Japanese divers are not the ones having problems, because the Japanese listen to the briefs and remove their snorkels from their mask, or failing that, never take the regs out from before the giant stride until they are back standing on the boat.
The people who have problems are the ones who try and use their snorkels. If you say you don't have people run into problems using snorkels then you don't, but that does not make them safer than not having one. I do see people using snorkels get into trouble because someone has told them that snorkels are "safety equipment" (that just gets them in trouble) or snorkels are useful to 'save air'. (I also get to see people orally inflate their BCDs to 'save air'.)
So choosing potential choking, or additional mask problems, in order to 'save air' on only some dives is, to me, obtuse.
This is why I am not sure what justification one can make to say that snorkels make things safer. If someone says people don't have problems caused by snorkels, that is ignoring the fact that snorkels do in fact cause problems underwater for your divers. (You mentioned this earlier, about the current making mask problems more likely for diver wearing snorkels.)
I am not coming at this with any assumptions about snorkels, being safe or not safe. I see snorkels causing problems and removing them solving them.
It seems like you are starting with the statement "Snorkels are safety equipment", and not budging off that even when presented with examples of them causing problems, instead saying it is the divers fault for not being better at whatever (mask clearing, snorkel breathing).
You see divers having snorkel-related problems, but despite that, you say wearing snorkels makes one safer. I see divers having snorkel related problems,
and see that removing them solves the problems, therefore I say snorkels make divers less safe. One of us is being obtuse, perhaps.
Are snorkels 'safety equipment' in the open ocean? Open ocean tech divers who do get stuck in the ocean for far longer with front slung tanks don't consider them as making things safer. Just the opposite. Because tech divers are not operating from old habit assumptions and they spend far longer at the surface, further away from shore than rec divers, they should be a good place to look to see if snorkels are being used. And they are not. In general tech divers consider them unsafe. I have seen some struggle to bring one along only to find the only ones flexible enough to carry safely are useless in real conditions.
Moreover snorkels use in waves is not useful even with a rigid snorkel. If one is stuck at the surface in the open ocean, far from boat or shore, the most important thing is to establish communication with someone (the boat, a search place, someone on shore). Putting one's face in the water does not help this at all. And it is not necessary. We all have some means of backup buoyancy (exposure protection if not a backup BCD), so we can get out face clear of the water, and we want our face clear of the water for safety reasons.
（I am not in the slightest but convinced that I would ever tell divers to ditch their gear and swim, but, like you, I can see me doing it as well if I was solo, stuck outside the cut. That's why I make the distinction between accomplished free divers carrying snorkels (where snorkels are a legitimate tool), and regular divers who are not in the ocean for a living (where they are a hazard, and must be stopped.)
Here's the deal: we are told by tradition that snorkels are safety equipment, so we think that baring evidence to the contrary, going along with that makes sense. But the fact is that there is plenty of evidence to the contrary, and we are just ignoring it. If we just starting the idea that a snorkel is a tool for a different job, and not a required part of an OW divers kit, then it would be hard to rationalize putting it on most divers.
